1. Field of the Invention
The present disclosure relates to a power adjustment method, and more particularly, to an electronic apparatus in a wireless local area network and a power adjustment method thereof.
2. Description of Related Art
At present, there are gradually more wireless communication apparatuses that support dual-mode systems, for example, supporting both worldwide interoperability for microwave access (WiMAX™) and wireless fidelity (Wi-Fi™) standards. WiMAX™ is a trademark of WiMAX Forum and is a term usually referring to a wireless communication technology and wireless communication system based on a series of IEEE 802.16 standards. IEEE 802.16 includes a series of standards developed by IEEE 802.16 committee. Wi-Fi™ is a trademark of Wi-Fi Forum and is a term usually referring to a wireless communication technology and wireless communication system based on a series of IEEE 802.11 standards. As used herein and throughout the present disclosure, the term “Wi-Fi™” refers to any communication network, system, equipment, apparatus, method, and the like, that utilizes or is based on the series of IEEE 802.11 standards. IEEE 802.11 includes a series of standards developed by IEEE 802.11 committee. The IEEE 802.11 committee establishes the standard relating to wireless local area network (WLAN). Some of the IEEE 802.11 standards specify the method for interaction between a wireless receiver and a wireless transmitter.
The series of IEEE 802.11 standards include: 802.11, established in 1997, which originally specifies 2 mega bits/per second(Mbps) data rate and the use of 2.4 giga hertz(GHz) frequency band; 802.11a, established in 1999, which provides physical layer supplements, for example, 54 Mbps data rate and 5 GHz band; 802.11b, established in 1999, which provides physical layer supplements, for example, 11 Mbps data rate and 2.4 GHz band; 802.11c, which adds MAC layer bridging complying with 802.1D; 802.11d, which adds support for “additional regulatory domains”; 802.11e, which adds support for quality of service (QoS); 802.11f, which adds interoperability between access point/base station; 802.11g, which provides physical layer supplements, for example, 54 Mbps data rate and 2.4 GHz band; 802.11h, which modifies the radius of the wireless service coverage and adds indoor and outdoor channels, for example, 5 GHz; 802.11i, which provides supplements relating to safety and authentication; 802.11n, which incorporates multiple-input-multiple-output (MIMO) and HT40 technology and is basically an extension version to 802.11a/g. In addition to the IEEE standards above, there is also a technology, called IEEE 802.11b+, which provides 22 Mbps data rate based on IEEE 802.11b (i.e. on 2.4 GHz band) by using a packet binary convolution code technology. In fact, IEEE 802.11b+ is a proprietary technology (owned by Texas Instruments®) rather than a published IEEE standard. There is also a technology, called IEEE 802.11g+, which provides 108 Mbps data rate based on IEEE 802.11g. Like the 802.11b+, the IEEE 802.11g+ is not a standard, either, but the SuperG™ technology that is advocated by Atheros®, a wireless network chip manufacturer.
Some of the dual-mode wireless communication apparatuses can be further configured as a hotspot communication apparatus which can not only access internet from its own wireless communication apparatus, but also can provide internet service to surrounding wireless communication terminal apparatus by using the WLAN technology.
However, the frequency bands of the two wireless communication systems supported by this type of hotspot communication apparatus may be close to each other or even overlapped. For example, the WiMAX system used by the hotspot communication apparatus may operate in 2.6 GHz band, while the Wi-Fi™ system used by the hotspot communication apparatus operates in 2.4 GHz band, such that the two wireless communication systems tend to interfere with each other. Especially when the hotspot communication apparatus increases the output power of the Wi-Fi™ system, the quality of the downlink signal of the WiMAX™ system received by the hotspot communication apparatus can be easily affected due to the adjacent-channel interference, and hence the overall wireless communication quality is impacted.
In order to avoid the interference between the dual wireless communication systems, one conventional approach is reducing and fixing the maximum of the Wi-Fi™ output power to pursue the stability of downlink data of specific WiMAX™ network. However, reducing the output power of the Wi-Fi™ system too much results in a small WLAN service coverage. For example, the minimal output power of the hotspot communication apparatus using Wi-Fi™ is about 0 dBm, which is far lower than the maximal allowable output power (18 dBm) of the Wi-Fi™ system. In practice, when the output power of a hotspot communication apparatus is 0 dBm, the Wi-Fi™ service coverage is about several meters. When the output power of the hotspot communication apparatus is 18 dBm, the Wi-Fi™ service coverage can be several hundred meters. As such, the conventional approach apparently limits the service coverage of the hotspot communication apparatus. What is needed, therefore, is a technique that can maintain a relative large output power to achieve relative large service coverage while not affecting the communication quality of the wireless wide area network.